US 5,928,300 AGranted

Three-axis aircraft crash sensing system

AssigneeSimula, Inc.

InventorsJon P. Rogers, Lindley W. Bark

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Abstract

An electronic crash sensing unit for detecting and discriminating a crash and actuating occupant safety device(s) such as air bags. The unit is designed and constructed to operate within an aircraft, but may be used in ground and sea-going vehicles as well. It provides crash acceleration sensing coverage for impact angles occurring throughout aircraft upper and lower hemispherical directions, which are defined by longitudinal, lateral, and vertical aircraft fixed axes as well as any combination of coordinates thereof. It can sense an aircraft acceleration event, determine if the acceleration is a normally occurring event not requiring air bag deployment or a crash event that warrants deployment. The crash sensing unit uses a microprocessor and algorithm to discriminate crash events that warrant safety device deployment from non-crash events, and to actuate deployment. The crash sensing unit compares continuously measured acceleration and calculated total velocity change to defined go/no-go threshold criteria. A crash event is defined as the exceeding both acceleration and velocity change thresholds.

Claims40

Dependent claims

A three-axis aircraft crash sensing system comprising:

(a) an x-axis solid-state accelerometer;
(b) a y-axis solid-state accelerometer mounted orthogonally to the x-axis solid-state accelerometer;
(c) a z-axis solid-state accelerometer mounted orthogonally to the x-axis and y-axis solid-state accelerometers;
(d) a microprocessor and one or more ignition circuits;
(e) one or more air bags;
and
(f) one or more gas generators, each of said gas generators comprising an igniter, wherein each igniter is electrically connected to an ignition circuit,
wherein said gas generators are capable of fully inflating all of the one or more air bags,
wherein each of the accelerometers continuously measures acceleration in its respective direction, and provides signals representative of the acceleration to the microprocessor,
wherein the microprocessor calculates an x-axis total velocity change, a y-axis total velocity change and a z-axis total velocity change from the signals representative of the acceleration,
wherein the microprocessor contains an x-axis total velocity change threshold, an x-axis acceleration threshold, a y-axis total velocity change threshold, a y-axis acceleration threshold, a z-axis total velocity change threshold and a z-axis acceleration threshold,
and wherein the microprocessor is programmed to issue a command to the ignition circuit to initiate ignition of one or more igniters if:
(i) the x-axis acceleration is greater than the x-axis acceleration threshold and the x-axis total velocity change is greater than the x-axis total velocity change threshold, or
(ii) the y-axis acceleration is greater than the y-axis acceleration threshold and the y-axis total velocity change is greater than the y-axis total velocity change threshold, or
(iii) the z-axis acceleration is greater than the z-axis acceleration threshold and the z-axis total velocity change is greater than the z-axis total velocity change threshold.

12 more elements

A method for detecting crashes comprising:

(a) providing a programmable controller and three solid-state accelerometers which are mounted in mutually orthogonal directions;
(b) continually receiving three sets of signals at the programmable controller from each of the three orthogonally-mounted solid-state accelerometers, each one of said set of signals representing the acceleration respectively experienced by one of the three solid-state accelerometers;
(c) comparing the acceleration measured by each of the three solid-state accelerometers to its respective acceleration threshold;
(d) returning to step (b) if the acceleration is determined to be not greater than the respective acceleration threshold for each of the three accelerometers;
(e) initializing a counter for time and a counter for total velocity change for each of the accelerometers for which the respective acceleration threshold was exceeded, if the acceleration is determined to be greater than the respective acceleration threshold for one or more of the three accelerometers;
(f) calculating the incremental velocity change;
(g) calculating the total velocity change by adding the incremental velocity change to a sum of all previously calculated incremental velocity changes within a predetermined time period, if any;
(h) comparing the total velocity change to a threshold velocity change threshold;
(i) if the total velocity change is greater than the threshold velocity change for any of the three accelerometers, igniting an ignition circuit which initiates generation of gas for inflating air bags;
and
(j) if the total velocity change is not greater than the threshold velocity change for any of the three accelerometers, returning to step (b).

8 more elements

A three-axis crash sensing system comprising:

(a) means for selecting a forward acceleration threshold, an aft acceleration threshold, an up acceleration threshold, a down acceleration threshold, a left acceleration threshold and a right acceleration threshold;
(b) means for selecting a forward total velocity change threshold, an aft total velocity change threshold, an up total velocity change threshold, a down total velocity change threshold, a left total velocity change threshold and a right total velocity change threshold;
(c) means for detecting forward acceleration, aft acceleration, up acceleration, down acceleration, left acceleration and right acceleration;
(d) means for calculating total velocity changes over a predetermined time period for the forward, aft, up, down, left and right directions from the detected respective forward, aft, up, down, left and right accelerations;
(e) means for comparing the detected forward, aft, up, down, left and right accelerations to the respective forward, aft, up, down, left and right acceleration thresholds;
(f) means for comparing the calculated forward, aft, up, down, left and right total velocity changes to the respective forward, aft, up, down, left and right total velocity change thresholds;
and
(g) means for determining whether air bags should be deployed based on the comparisons of the respective accelerations to the respective acceleration thresholds, and the comparisons of the respective total velocity changes to the respective total velocity change thresholds.

5 more elements

A three-axis aircraft crash sensing system comprising:

(a) an x-axis solid-state accelerometer;
(b) a y-axis solid-state accelerometer mounted orthogonally to the x-axis solid-state accelerometer;
(c) a z-axis solid-state accelerometer mounted orthogonally to the x-axis and y-axis solid-state accelerometers;
(d) a microprocessor and one or more ignition circuits;
(e) one or more air bags;
and
(f) one or more gas generators, each of said gas generators comprising an igniter, wherein each igniter is electrically connected to an ignition circuit,
wherein said gas generators are capable of fully inflating all of the one or more air bags,
wherein each of the accelerometers continuously measures acceleration in its respective direction, and provides signals representative of the acceleration to the microprocessor,
wherein the microprocessor calculates an x-axis total velocity change, a y-axis total velocity change and a z-axis total velocity change from the signals representative of the acceleration,
wherein the microprocessor contains an x-axis acceleration threshold, a y-axis acceleration threshold, and a z-axis acceleration threshold,
wherein the microprocessor also contains an x-axis total velocity change threshold, a y-axis total velocity change threshold and a z-axis total velocity change threshold,
wherein the microprocessor also contains an equation for calculating whether an acceleration criterion has been exceeded based upon the measured x-axis, y-axis and z-axis accelerations, and upon the x-axis, y-axis and z-axis acceleration thresholds,
wherein the microprocessor also contains an equation for calculating whether a total velocity change criterion has been exceeded based upon the calculated x-axis, y-axis and z-axis total velocity changes, and upon the x-axis, y-axis and z-axis total velocity change thresholds,
and wherein the microprocessor is programmed to issue a command to the ignition circuit to initiate ignition of one or more igniters if the acceleration criterion has been exceeded and the total velocity change criterion has been exceeded.

12 more elements

A method for detecting crashes comprising:

(a) providing a programmable controller and three solid-state accelerometers which are mounted in mutually orthogonal directions;
(b) continually receiving three sets of signals at the programmable controller from each of the three orthogonally-mounted solid-state accelerometers, each one of said set of signals representing the acceleration respectively experienced by one of the three solid-state accelerometers;
(c) calculating whether an acceleration criterion has been exceeded based upon the measured x-axis, y-axis and z-axis accelerations, and upon x-axis, y-axis and z-axis acceleration thresholds,
(d) returning to step (b) if the acceleration criterion has not been exceeded;
(e) initializing a counter for time and a counter for total velocity change for each of the accelerometers for which the respective acceleration threshold was exceeded, if the acceleration criterion has been exceeded;
(f) calculating the incremental velocity change for the x-direction, and incremental velocity change for the y-direction and an incremental velocity change for the z-direction;
(g) calculating the total velocity change for each of the x, y and z directions by adding the incremental velocity change to a sum of all previously calculated incremental velocity changes for that direction within a predetermined time period, if any;
(h) calculating whether a total velocity change criterion has been exceeded based upon the total velocity changes for the x, y and z directions, and also based upon total velocity change thresholds for the x, y and z directions;
(i) if the total velocity change criterion has been exceeded, igniting an ignition circuit which initiates generation of gas for inflating air bags;
and
(j) if the total velocity change criterion has not been exceeded, returning to step (b).

8 more elements

Dependencies are inferred from the claim text.